Cardiac-active pharmaceutical compositions containing a cardenolide glycoside

ABSTRACT

CARDIAC-ACTIVE PHARMACEUTICAL COMPOSTIONS CONTAINING AS AN ACTIVE INGREDIENT A CARDENOLIDE GLYCOSIDE OF THE FORMULA   3-A,12-R1,17-(4-X,5-(O=)-2,5-DIHYDROFUR-3-YL)ANDROSTAN-   14-OL   WHEREIN R1 IS HYDROGEN, HYDROXYL OR ALKANOYLOXY OF 1 TO 3 CARBON ATOMS, X IS CHLORINE, FLUORINE OR ALKOXY OF 1 TO 4 CARBON ATOMS, AND A IS DIGITOXOSYL OF THE FORMULA   (4-(R2-O-),5-((4-(R2-O-),5-((4,5-DI(R2-O-),6-CH3-TETRA-   HYDROPYRAN-2-YL)-O-),6-CH3-TETRAHYDROPYRAN-2-YL)-O-),   6-CH3-TETRAHYDROPYRAN-2-YL)-O-   WHRE R2 IS HYDROGEN OR ALKANOYL OF 1 TO 3 CARBON ATOMS AND A METHOD OF PRODUCING A POSITIVE INOTROPIC ACTION UPON THE HEART OF A WARM-BLOODED AANIMAL.

.United States Patent Int. Cl. A61k 27/10 US. Cl. 424-182 6 Claims ABSTRACT OF THE DISCLOSURE Cardiac-active pharmaceutical compositions containing as an active ingredient a cardenolide glycoside of the formula wherein R is hydrogen, hydroxyl or alkanoyloxy of 1 to 3 carbon atoms, X is chlorine, fluorine or alkoxy of 1 to 4 carbon atoms,

A is digitoxosyl of the formula no ga R20 R:

where R is hydrogen or alkanoyl of 1 to 3 carbon atoms;

and a method of producing a positive inotropic action upon the heart of a warm-blooded animal.

This is a division of copending application Ser. No. 43,198 filed June 3, 1970, now US. Pat. No. 3,696,091 issued Oct. 3, 1972.

This invention relates to novel cardiac-active pharmaceutical compositions containing cardenolide glycosides as active ingredients, as well as to a novel method of producing a positive inotropic action upon the heart of a warm-blooded animal.

More particularly, the present invention relates to cardiac-active pharmaceutical compositions containing as Patented Apr. 9, 1974 an active ingredient a cardenolide glycoside compound of the formula wherein R is hydrogen, hydroxyl or alkanoyloxy of 1 to 3 carbon atoms,

X is chlorine, fluorine or alkoxy of 1 to 4 carbon atoms,

and

A is digitoxosyl of the formula lgyr where R; is hydrogen or alkanoyl of 1 to 3 carbon atoms.

A cardenolide glycoside of the Formula I is prepared by intra-molecular cyclization of a steroid ester of the formula H (II) wherein X has the same meanings as in Formula I,

R is hydrogen, acyloxy, or a hydroxyl group which is protected by another easily removable protective radical, such as trialkylsiyl, tetrahydropyranyl or trichloroethylcarbonyl,

R is lower alkyl, and

A is digitoxosyl of the formula 0 a I e 0 "0'" Kl)! R20 0R2 where R is acyl or another easily removable protective radical, such as trialkylsilyl, tetrahydropyranyl or trichloroethylcarbonyl, in the presence of a base.

In those instances where the starting compound of the Formula II is one in which the substituents R and/or R are protected groups different from the desired substituents R and R respectively, in the end product of the Formula I, the protective groups in the intermediate cardenolide glycoside are split oil? and the resulting compound of the Formula I wherein R is hydroxy and/r R is hydrogen is subsequently acylated, if so desired.

The intra-molecular cyclization is performed in the presence of a base, such as an alkali metal alcoholate, an alkali metal hydride, and alkali metal amide, an alkali metal hydroxide or an alkali metal carbonate, and advantageously in the presence of an inert organic solvent, such as dimethylglycol ether, at temperatures between 40 and +50 C., preferably between 0 and +20 C.

In addition to the above-mentioned protective groups for hydroxyl groups, all other customary protective groups for hydroxyl may be employed, such as benzyl, carbobenzoxy, benzoyl, phosphonoacyl or the like.

The removal of the acyl or phosphonoacyl protective groups may, for example, be effected by mild alkaline or acid hydrolysis; the removal of benzyl or carbobenzoxy protective groups may, for instance, be eifected by means of catalytic hydrogenation; and trimethylsilyl or tetrahydropyranyl protective groups may be removed by treatment with dilute acids.

The optional acylation of a compound of the Formula I, wherein R is hydroxyl and/or R is hydrogen, may be effected by reaction with carboxylic acid anhydride or a carboxylic acid halide, for example.

If the starting compound of the Formula II for the intra-molecular cyclization is one wherein the protective groups are already identical to the desired acyl radicals R; and/or R, in Formula I, the cyclization yields the desired acyl-substituted compound of the Formula I directly.

The steroid esters of the Formula II used as starting compounds for the intra-molecular cyclization are themselves new compounds. These steroid esters are prepared by esterification of an a-ketol of the formula CH2 OH wherein A and R have the same meanings as in Formula II, with a phosphono-acid of the formula wherein R and X have the same meanings as in Formulas II and 1, respectively.

The esterification is advantageously carried out in an inert organic solvent, for example in benzene, preferably in the presence of a dehydrating agent, such as dicyclo hexyl-carbodiimide, or carbonylor thionyl-N,N'-diimidazole, at temperatures between -20 and +50 C., preferably at 20 C. The reaction may also be performed with the reactive derivatives of a phosphono-acid of the Formula IV produced in situ, for example m'th its acid halides or anhydrides, advantageously in the presence of an acid-binding agent, for instance a tertiary organic base, such as pyridine, or an inorganic base.

If the esterification is performed with the ketol obtained from digitoxin or digoxin and with a phosphonoacid of the Formula IV, a starting material of the Formula H is obtained in which the protective groups represent a corresponding phosphonoacyloxy or phosphonoacyl group.

(III) The a-ketols of the Formula III are produced according to methods known from the literature [see, for example, K. Meyer and T. Reichstein, Helv. Chim. Acta 30, 1508 (1947)].

Some of the phosphono-acids of the Formula IV are known from the literature. They may be prepared from the corresponding phosphono-acid esters by mild equimolar alkaline hydrolysis, by subsequent acidification with a mineral acid and extraction with an organic solvent [see, for example, H. W. Kofen, J. Amer. Chem. Soc. 79, 1963 (1957); W. Grell and H. Machleidt, Liebigs Ann. Chem. 693, 134 (1966) and 699, 53 (1966); D. J. Martin and C. E. Griflin, J. Org. Chem. 30, 4034 (1965); and G. Ackermann, J. Amer. Chem. Soc. 79, 6524 (1957)].

The following examples illustrate the preparation of compounds of the Formula I.

EXAMPLE 1 (a) 22-n-butoxy-digitoxin tetraacetate 8 gm. (8.8 millimols) of 35-[O-(3,4-di-O-acetyl-B-D- digitoxosyl)-(1 4)-O-(3-O-acetyl-;3 D-digitoxosyl 1-) 4)-(3-O-acetyl-fi-D-digitoxosyl)] 33,145-21-trihydroxy- 20-oxo-5;9-pregnane were dissolved in 120 ml. of absolute benzene and, while cooling the solution with ice, first a solution of 3.1 gm. of a-diethyl-phosphono-Z-n-butoxyacetic acid (11.5 millimols) in 10 ml. of benzene and then a solution of 2.5 gm. (12.1 millimols) of N,N'- dicyclohexylcarbodiirnide in 10 ml. of benzene were added to the reaction mixture. After stirring for 3 to 4 hours at room temperature, the N,N'-dicyclohexy1-urea which precipitated during the reaction was filtered off, and the filtrate was evaporated to dryness in vacuo. The residual oily foam was 3 8-[0-(3,4-di-O-acetyl-fi-D-digitoxosyl)- (1- 4)-(3-O acetyl-B-D-digitoxosyD] 3p,l4B,2l-trihydroxy-21-(2-diethyl-phosphono 2 n-butoxy-acetyl)-20- oxo-5fl-pregnane, R -valuez 0.3 (silica gel; solvent system: ethyl acetate/benzene=4/ 1).

The obtained crude product was taken up in 120 ml. of dimethylglycol, and 1.33 gm. (11.9 millimols) of potassium tert.-butylate were added to the solution while cooling with ice. After standing for one hour at room temperature the reaction solution was poured into 250 ml. of dilute hydrochloric acid and extracted with chloroform; The combined extracts were washed, dried and evaporated in vacuo. For further purification the crude product was subjected to chromatography on silica gel (system:benzene/ethyl acetate=19/l0). Yield: 3.4 gm. (38% of theory). [a] +51 (in methanol, c.=0.76). R =value: 0.7 (silica gel; solvent system: ethyl acetate/ benzene=4/1).

(b) 22-n-butoxy-digitoxin 2.8 gm. (2.78 millimols) of 22-n-butoxy-digitoxin-tetraacetate were dissolved with 2.3 gm. (13.2 millimols) of potassium carbonate in 200 m1. of methanol by addition of 5 ml. of water, and the solution was stirred for about two hours at 50-60 C. After completion of the reaction, the solution was diluted with ethyl acetate, dried with sodium sulfate and, after filtration, the solvent was removed from the filtrate in vacuo. The residue was subjected to chromatography on silica gel (system: ethyl acetate/ethanol=20/ 1). Yield: 2.1 gm. of theory). [a] =-+6.5 (in methanol, c.=1.3). R =valuez 0.65 (silica gel; solvent system: ethyl acetate/ethanol=87/l3).

EXAMPLE 2 (a) ZZ-methyl-digitoxin-tetraacetate Analogous to Example 1(a), starting from 8 gm. (8.8 millimols) of 3B-[O-(3,4-di-O-acetyl-fi-D-digitoxosyl) (1- 4) 0 (3-O-acetyl-{3-D-digitoxosyl)-(1- 4)-(3-O- acetyl-pS-D-digitoxosyl)]-3fi,14p,21trihydroxy 20 oxo- Sfi-pregnane and 2.4 gm. (11.4 millimols) of Z-diethylphosphono-Z-methylacetic acid, and condensation with 2.5 gm. (12.1 millimols) of dicyclohexylcarbodiimide, the

corresponding a-ketol-phosphono-ethyl acetate was obtained. R -value: 0.2 (silica gel; solvent system: ethyl acetate/benzene=4/ 1 Upon treating the obtained product with 1.33 gm. (11.9 millimols) of potassium tert.-butylate, 2.6 gm. (31% of theory) of 22-methyl-digitoxin tetraacetate were obtained which were subjected to chromatography on silica gel (system: benzene/ethyl acetate=17/10). [od =+55 (in methanol, c.=l.9). R =valuez 0.65 (silica gel; solvent system: ethyl acetate/benzene=4/ 1).

(b) 22-methyl-digitoxin Analogous to Example 1(b), starting from 2 gm. (2.11 millimols) of 22-methyl-digitoxin tetraacetate and hydrolysis with 1.74 gm. millimols) of potassium carbonate in 195 ml. of methanol and 10 ml. of water, 1.2 gm. (73.5% of theory) of 22-methyl-digitoxin were obtained, which were subjected to chromatography on silica gel (system: ethyl acetate). [a] -=-|-7.9 (in methanol, c.=l.1). R =value: 0.65 (silica gel; solvent system: ethyl acetate/ ethanol: 87/ 13) EXAMPLE 3 (a) 22-methoxy-digitoxin tetraacetate Analogous to Example 1(a), starting from 8 gm. (8.8 millimols) of 3B-[O-(3,4-di-O-acetyl-B-D-digitoxosyl)- (1 4) O (3-O-acetyl-pl-D-digitoxosyl)-(1 4)-(3-0 acetyl-fi-D-digitoxosyl)]3 3,14 3,21-trihydroxy oxo- Sit-pregnane and 2.6 gm. (11.5 millimols) of 2-diethylphosphono-2-methoxyacetic acid and condensation with 2.6 gm. (12.1 millimols of dicyclohexylcarbodiimide, the corresponding a-ketol-phosphono-ethyl acetate was obtained. R -valuez 0.3 (silica gel; solvent system: ethyl acetate/benzene=4/ l Upon treating the obtained product with 1.33 gm. (11.9 millimols) of potassium tert.-butylate, 2.2 gm. (26% of theory) of 22-methoxy-digitoxin tetraacetate were obtained. The raw product was purified by chromatography on silica gel. (System: benzene/ethyl acetate=l7/10). [a] =+54 (in methanol, c.=1.7). R -value: 0.7 (silica gel; solvent system: ethyl acetate/benzene=4/ 1).

(b) 2.2-methoxy-digitoxin Analogous to Example 1(b), starting from 1.5 gm. (1.56 millimols) of 22-methyl-digitoxin tetraacetate and hydrolysis with 1.29 gm. (7.4 millimols) of potassium carbonate in 145 ml. of methanol and 5 ml. of water, 1.0 gm. (81% of theory) of 22-methoxy-digitoxin was obtained, which was subjected to chromatography on silica gel (system: benzene ethanol=20/l). [a] =|-9.8 (in methanol, c.-=1.2). R value: 0.65 (silica gel; solvent system: ethyl acetate/ethanol=87/13).

EXAMPLE 4 (a) 22-ethoxy-digitoxin tetraacetate Starting from 8 gm. (8.8 millimols) of 3,9-[O-(3,4-di O-acetyl B D digitoxosyl) (l 4) O (3 O- acetyl-B-D-digitoxosyl) (1 4) (3 O acetyl-fi-D- digitoxosyl)] 318,145,21 trihydroxy-ZO-oxo-5;8-pregnane and 2.75 gm. (11.5 millimols) of Z-diethylphosphono-Z- ethoxy-acetic acid and condensation with 2.5 gm. (12.1 millimols) of dicyclohexylcarbodiimide analogous to Example 1(a), the corresponding a-ketolphosphono-ethyl acetate was obtained. R -valuez 0.25 (silica gel; solvent system: ethyl acetate/benzene=4/1).

Upon treating the obtained product with 1.33 gm. 11.9 millimols) of potassium tert.-butylate, 2.9 gm. (34% of theory) of 22 ethoxy digitoxin tetraacetate were obtained, which were subjected to chromatography on silica gel (system: benzene/ ethyl acetate= 18/ 10) (in methanol, c.=1.1). R -value: 0.7 (silica gel; solvent system: ethyl acetate/-benzene=4/1).

(b) 22-ethoxy-digitoxin Starting from 2.3 gm. (2.35 millimols) of 22-ethoxydigitoxin tetraacetate and hydrolysis with 1.93 gm. (11.1 millimols) of potassium carbonate in aqueous methanol analogous to Example 1(a), 1.8 gm. (94% of theory) of 22-ethoxy-digitoxin were obtained, which were subjected to chromatography on silica gel (system: ethyl acetate/ ethanol=20/1). Yield: 1.3 gm. (94% of theory).

(in methanol, c.=0.7). R -value: 0.65 (silica gel; solvent system: ethyl acetate/ethanol=87/ 13).

EXAMPLE 5 (a) 22-methoxy-digoxin pentaacetate Analogous to Example 1(a), starting from 10 gm. (10.3 millimols) of 3 3-[O-(3,4-di-O-acetyl-;8-D-digitoxosyl) (.1- 4) O (3 O acetyl 8 D digitoxosyl)- (1 4) (3 O acetyl B D digitoxosyl)] 35,1213, 14,8,2l-tetrahydroxy-1213-acetyl-20-oxo-5f3 pregnane and 5.4 gm. (24 millimols) of 2-diethylphosphono-2-methoxyacetic acid and condensation with 5.0 gm. (24 millimols) of dicyclohexylcarbodiimide, the corresponding a-ketolphosphono-ethyl acetate was obtained. R -value: 0.15 (silica gel; solvent system: ethyl acetate/benzene=4/1).

Upon treating the obtained product with 2.74 gm. (24 millimols) of potassium tert.-butylate, 1.85 gm. (17.6% of theory) of 22-methoXy-digoxin pentaacetate were obtained, which were subjected to column chromatography on silica gel (system: benzene/ethyl acetate=2/1). [a] +63" (in methanol, c.=1). R -value: 0.65 (silica gel; solvent system: ethyl acetate/benzene=4/1).

(b) 22-methoxy-digoxin Starting from 1.0 gm. (0.98 millimols) of 22-methoxydigoxin pentaacetate and hydrolysis with 600 mgm. (3.4 millimols) of potassium carbonate in ml. of aqueous methanol analogous of Example 680 mgm. (75.5% of theory) of 22-methoxy-digoxin were obtained, which were subjected to chromatography on silica gel (system: ethyl acetate/ethanol=4/1). [a] =+17 (in methanol, c.'=0.7). R -value: 0.55 (silica gel; solvent system: ethyl acetate/ethanol=87/ l3).

EXAMPLE 6 (a) 22-ethoxy-digoxin pentaacetate Starting from 9.67 gm. 10 millimols) of 3 3-[O-(3,4- di O acetyl )8 D digitoxosyl) (1 4) 0 (3 O- acetyl B D digitoxosyl) (1- 4) (3 O acetyl ,8- D digitoxosyl)] 3/3,12fl,14B,21 tetrahydroxy 12B- acetyl-ZO-oxo-5fl-pregnane and 3.12 gm. (13 millimols) of 2-diethylphosphono-2-ethoxy-acetic acid and condensation with 2.9 gm. (14 millimols) of dicyclohexyl-carbodiimide analogous to Example 1(a), the corresponding aketol-phosphono-ethyl acetate was obtained. R -valuez 0.25 (silica gel; solvent system: ethyl acetate/benzene=4/ 1 Upon treating the obtained product with 1.5 gm. (13.4 millimols) of potassium tert.-butylate, 2.5 gm. (24% of theory) of 22-ethoxy-digoxin pentaacetate were obtained, which were subjected to column chromatography on silica gel (system: benzene/ethyl acetate=16/10).

(in methanol, c.=2.'4). R -value: 0.6 (silica gel; solvent system: ethyl acetate/benzene=4/ 1).

(b) 22-ethoxy-digoxin Starting from 1.0 gm. (1 millimol) of 22-ethoxy-di-goxin pentaacetate and hydrolysis with 1.0 gm. (5.7 millimols) of potassium carbonate in 100 ml. of aqueous methanol analogous to Example 1(b), 800 mgm. (97% of theory) of 22-ethoxy-digoxin were obtained, which were subjected to chromatography on silica gel (system: ethyl acetate/ethanol=/ 1). [a] =+15 (in methanol, c.=l.1). R value: 0.6 (silica gel; solvent system: ethyl acetate/ethanol=87/ 13).

EXAMPLE 7 (a) 22-n-butoxy-digoxin pentaacetate Starting from 9.67 gm. millimols) of 3 3-[0-(3,4- di O acetyl {3 D digitoxosyl) (1- 4) O (3 O- acetyl B D digitoxosyl) (1 4) (3 O acetyl 3 D digitoxosyD] 3,8,12 3,14,21 tetrahydroxyl2B-acetyl-20-oxo-SB- regnane and 3.5 gm. (13 millimols) of 2-diethylphosphono-Z-n-butoxy-acetic acid and condensation with 2.9 gm. (l4 millimols) of dicyclohexylcarbodiimide analogous to Example 1(a), the corresponding a-ketol-phosphono-ethyl acetate was obtained. R;- value: 0.2 (silica gel; solvent system: ethyl acetate/benzene =4/ l).

Upon treating the obtained product with 1.5 gm. (13.4 millimols) of potassium tert.-butylate, 3.1 gm. (29% of theory) of 22-n-butoxy-digoxin pentaacetate were obtained, which were subjected to column chromatography on silica gel (system: benzene/ethyl acetate=2/1). [a] =+71 (in methanol, c.=1.2). R value: 0.6 (silica gel; solvent system: ethyl acetate/benzene=4/1).

(b) 22-n-butoxy-digoxin Starting from 1.56 gm. (1 millimol) of 22-n'butoxydigoxin pentaacetate and hydrolysis with 1.0 gm. (5.75 millimols) of potassium carbonate in 100 ml. of aqueous methanol analogous to Example 1(b), 550 mgm. (65% of theory) of 22-n-butoxy-digoxin were obtained, which were subjected to chromatography on silica gel (system: ethyl acetate/ethanol=25/1). [a] -=+12.8 (in methanol, c. =1). R value: 0.65 (silica gel; solvent system: ethyl acetatelethanol= 87/ 13).

EXAMPLE 8 (a) 22-methyl-digoxin pentaacetate Starting from 9.67 gm. (10 millimols) of 3fi-[O-(3,4- di-o-acetyl-p-D-digitoxosyl) (1- 4)-O-(3-O-acetyl-,B-D- digitoxosyl)-(1- 4)-(3 O acetyl-p-D-digitoxosyl)]3 8, 1249,1433 l-tetrahydroxy 128 acetyl-20-oxo-5p-pregnane and 2.73 gm. (13 millimols) of Z-diethyl-phosphono-Z- methyl-acetic acid and condensation with 2.9 gm. (l4 millimols) of dicyclohexylcarbodiimide analogous to Example 1(a), the corresponding a-ketol-phosphono-ethyl acetate was obtained. R -valuez 0.25 (silica gel; solvent system: ethyl acetate/benzene=4/1).

Upon treating the obtained product with 1.5 gm. (13.4 millimols) of potassium tert.-butylate, 3 gm. (30% of theory) of ZZ-methyl-digoxin pentaacetate were obtained, which were subjected to column chromatography on silica gel (system: benzene/ethyl acetate=2/1). [u] =+69 (in methanol, c.=1.7). R value: 0.6 (silica gel; solvent system: ethyl acetate/benzene=4/1).

(b) 22-methyl digoxin Starting from 1.0 gm. (1 millimol) of 22-methyldigoxin pentaacetate and hydrolysis with 1.0 gm. (5.75 millimols) of potassium carbonate in 100 ml. of aqueous methanol analogous to Example 1(1)), 500 mgm. (63% of theory) of 22-methyl-digoxin were obtained, which were subjected to column chromatography on silica gel (system: ethyl acetate/ethanol=25/1). [a] =+10 (in methanol, c.=0.4). R -value: 0.6 (silica gel; solvent system: ethyl aoetate/ethanol=87/ 13).

EXAMPLE 9 (a) 22-fluoro-digitoxin tetraacetate Starting from 11 gm. (12.1 millimols) of 3fl-[O-(3,4- di 0 acetyl-B-D-digitoxosyl)-(1 4)-O-(3-Q-acetyl-fl- D-digitoxosyl) (1 4) (3-O-acetyl-p-D-digrtoxosyl)]- 35,145,21 trihydroxy 20 oxo-Sfi-pregnane and 3.4 gm. (15.8 millimols) of 2 diethyl-phosphono-Z-fiuoro-acetic acid and condensation with 3.45 gm. (16.7 millimols) of dicyclohexylcarbodiimide analogous to Example 1(a), 13 gm. (97% of theory) of the corresponding u-ketol-phosphone-ethyl acetate were obtained. R value: 0.35 (silica gel; solvent system: ethyl acetate/benzene=4/ 1).

Upon treating the obtained product (14 gm.=12.7 millimols) with 1.80 gm. (16.0 millimols) of potassium tert.-butylate, 5.1 gm. (42.5% of theory) of 22-fluorodigitoxin tetraacetate were obtained, which were subjected to chromatography on silica gel (system: benzene/ ethyl acetate=2/1). [a] =|-60 (in methanol, c. =1.8). R -value: 0.7 (silica gel; solvent system: ethyl acetate/benzene=4/1).

(b) 22-fluoro-digitoxin Starting from 3.5 gm. (3.7 millimols) of 22-fluorodigitoxin tetraacetate and hydrolysis with 50 ml. of absolute methanol half-saturated with ammonia, 1.2 gm. (42% of theory) of 22-fluoro-digitoxin were obtained, which were subjected to chromatography on silica gel (system: ethyl acetate/benzene=4/ 1), MP. 237-239 C. (decomp.: from ethyl acetate). [u] =+18 (in methanol, c.= 0.4). R value: 0.6 (silica gel; solvent system: ethyl acetate/ethanol=87/ 13).

EXAMPLE 10 (a) 22-fluoro-digoxin pentaacetate Analogous to Example 1(a), starting from 11.7 gm. (12.1 millimols) of 35-[0-(3,4 di 0 acetyl-fl-D-digitoxosyl) (1- 4)-O-(3-O-acetyl-p-D-digitoxosyl)-( 1- 4)- (3-O-acetyl-p-D-digitoxosyl)] 3p,12,8,14;8,21 tetrahydroxy-l2,9-acetyl-20-oxo-5fi-pregnane and 3.4 gm. (15.8 millimols) of 2-diethylphosphono-Z-fluoro-acetic acid and condensation with 3.45 gm. (16.7 millimols) of dicyclohexylcarbodiimide analogous to Example 1(a), 12 gm. of theory) of the corresponding a-ketol-phosphonoethyl acetate were obtained. R value: 0.20 (silica gel; solvent system: ethyl acetate/benzene=4/ 1).

Upon treating the obtained product (14 gm.=12 millimols) with 1.8 gm. (16 millimols) of potassium tert. butylate, 3.5 gm. (29% of theory) of 22-fluoro-digoxin pentaacetate were obtained, which were then subjected to chromatography on silica gel (system: benzene/ ethyl acetate=2/1). [a] =+7-4 (in methanol, c.=l.l). R;- value: 0.30 (silica gel; solvent system: ethyl acetate/benzene=1/1).

(b) 22-fluoro-digoxin Analogous to Example 1(b), starting from 3.0 gm. (3 millimols) of 22-fluoro-digoxin pentaacetate and hydrolysis with 50 ml. of absolute methanol half-saturated with ammonia, 1.5 gm. (63% of theory) of 22-fluoro-digoxin were obtained, which were subjected to chromatography on silica gel (system: ethyl acetate/'benzene=6/1). [a] -=+23 (in methanol, c.=0.4). -R;-value: 0.55 gilica gel; solvent system: ethyl acetatelethanol=87l EXAMPLE 11 (a) 22-chloro-digoxin pentaacetate Starting from 11.4 gm. (11.8 millimols) of 3,8-[O-(3,4- di-O-acetyl-fi-D-digitoxosyl)-(1- 4)-O-(3 O acetyl ,8- D-digitoxosyl)-(1 4)-(3-O-acetyl i3 D digitoxosyl) 3 3,12fi,14,6,2l-tetrahydroxy-lZfi-acetyl 30 oxo-Sfl-pregnane and 4 gm. (17.3 millimols) of Z-diethylphosphono- Z-chloro-acetic acid and condensation with 3.82 gm. (18.5 millimols) of dicyclohexylcarbodiimide analogous to Example l(a), 12.6 gm. (91% of theory) of the corresponding a-ketol-phosphono-ethyl acetate were obtained. R value: 0.20 (silica gel; solvent system: ethyl acetate/benzene=4/ 1 Upon treating the obtained product (15 gm.-=12.7 millimols) with 2.0 gm. (17.8 millimols) of potassium tert.- butylate, 3.0 gm. (23% of theory) of 22-chloro-digoxin zene=1/ 1 EXAMPLE 12 (a) 22-n-butyl-digoxin pentaacetate Starting from 7.4 gm. (7.65 millimols) of 3B-[O-(3,4- di-O-acetyl-fl-D-digitoxosyl)-(1- 4)-O-( 3 O acetyl 13- D-digitoxosyl)-(1 4)-(3-O-acetyl B D digitoxosyl) 313,12B,14,8,2l-tetrahydroxy-12,8-acetyl 20 oxo-Sfi-pregnane and 2.52 gm. (10 millimols) of Z-diethylphosphono- 2-n-butyl-acetic acid and condensation with 2.27 gm. (11 millimols) of dicyclohexylcarbodiimide analogous to Example 1(a), 8.5 gm. (92.5% of theory) of the corresponding a-ketol-phosphono-ethyl acetate were obtained. R;- value: 0.10 (silica gel; solvent system: ethyl acetate/benzene=4/ l Upon treating the obtained product (9 gm.=7.5 millimols) with 1.15 gm. (10.2 millimols) of potassium tert.- butylate 1.2 gm. (15% of theory) of 22-n-butyl-digoxin pentaacetate were obtained, which were subjected to chromatography on silica gel (system: benzene/ethyl acetate=2/1). [a] =+57 (in methanol, c.=1.3). R;- value: 0.35 (silica gel; solvent system: benzene/ethyl acetate: 1/1

(b) 22-n-butyl-digoxin Starting from 0.65 gm. (0.62 millimol) of 22-n-butyldigoxin pentaacetate and hydrolysis with 0.62 gm. (3.56 millimols) of potassium carbonate in 50 m1. of methanol and 2 ml. of water analogous to Example 1(b), 520 mgrn. (98% of theory) of 22-n-butyl-digoxin were obtained, which were subjected to chromatography on silica gel system: ethyl acetate/ethanol=20/ l). [a] =|5.4 (in methanol, c.=0.5). R -valuez 0.55 (silica gel; solvent system: ethyl acetate/ethanol=87/ 13).

EXAMPLE 13 (a) 22-n-butyl-digitoxin tetraacetate Starting from 6.95 gm. (7.65 millimols) of 3fl-[O(3,4- di-O-acetyl-B-D-digitoxosyl)-(1- 4)-O-(3 O acetyl 13- O-digitoxosyl)-(l 4)-(3-O-acetyl 3 D digitoxosyl)]- 35,143,21-trihydroxy 20 oxo-SB-pregnane and 2.52 gm. (l millimols) of 2-diethylphosphono-2-n-butyl-acetic acid and condensation with 2.27 gm. (11 millimols) of dicyclohexylcarbodiimide analogous to Example 1(a), 8 gm. (91.5% of theory) of the corresponding a-ketol-phosphono-ethyl acetate .were obtained. R -value: 0.15 (silica gel; solvent system: ethyl acetate/benzene=4/1).

Upon treating the obtained product (8.8 gm.=7.8 millimols) with 1.15 gm. (10.2 millimols) of potassium tert.- butylate, 1.1 gm. (14.5% of theory) of 22-n-butyl-digitoxin tetraacetate were obtained, which were then subjected to chromatography on silica gel (system: benzene/ ethyl acetate=2/1). [a] =+50 (in methanol; c.=0.7). R -value: 0.4 (silica gel; solvent system: ethyl acetate/ benzene=l/1).

(b) 22-n-butyl-digitoxin Starting from 0.55 gm. (0.557 millimol) of 22-n-butyldigitoxin tetraacetate and hydrolysis with 0.45 gm. (2.58 millimols) of potassium carbonate in 50 ml. of methanol and 2 ml. of water analogous to Example 1(b), 400 mgm. (88% of theory) of 22-n-butyl-digitoxin were obtained, which were subjected to chromatography on silica gel (system: ethyl acetate/ethanol=20/1). [a] =+9.2 (in methanol, c.=0.7). R -value: 0.6 (silica gel; solvent system: ethyl acetate/ benzene: l 1).

EXAMPLE 14 22-methyl-digitoxin tetraacetate A mixture consisting of 0.2 gm. (0.25 millimol) of 22-methyl-digitoxin, 20 ml. of pyridine and 20 ml. of acetanhydride was allowed to stand for four days at room temperature. After completion of the reaction the tetraacetate formed thereby was precipitated by addition of ice water. The precipitate was dissolved in ethyl acetate, and the solution was extracted twice with aqueous 5% sodium bicarbonate and water, dried over sodium sulfate and evaporated to dryness in vacuo. 0.23 gm. (95% of theory) of 22-methyl-digitoxin tetraacetate were obtained by chromatography on silica gel. R -valuez 0.66 (silica gel; solvent system: ethyl acetate/benzene=4/1). [u] =-|55 (in methanol, c.=1.9).

EXAMPLE 15 (a) 22-fluoro-digitoxin tetra-trichloroethylcarbonate Starting from 1.8 gm. (1.118 millimols) of 35-[O-(3,4- di O trichloroethoxycarbonyl-fi-D-digitoxosyl)-(1- 4)- O-(3-O trichloroethoxycarbonyl-p-D-digitoxosyD-(1 4)- O-(3 O trichloroethoxycarbonyl p D digitoxosyl) 143,21-dihydroxy-5;3-pregnane 20 one and 0.314 gm. (1.46 millimols) of 2-diethylphosphono 2 fluoro-acetic acid and condensation with 0.32 gm. (1.545 millimols) of dicyclohexylcarbodiimide analogous to Example 1(a), 2.16 gm. of the corresponding a-ketol-phosphono-ethyl acetate was obtained. R -valuez 0.65 (silica gel; solvent system: ethyl acetate).

Upon treating the obtained product with 0.166 gm. (1.47 millimols) of potassium tert.-butylate, 0.6 gm. (32.5% of theory) of the compound named in the title of this example was obtained. R -value: 0.75 (silica gel; solvent system: ethyl acetate).

(b) 22 fluoro-digitoxin 0.6 gm. (0.363 millimols) of 22-fluoro-digitoxin tetratrichloroethylcarbonate were dissolved in 10 ml. of glacial acetic acid and the solution was shaken vigorously for minutes in the presence of 0.5 gm. of zinc powder. Then, the reaction mixture was filtered, the filtrate was diluted with water and extracted several times with ethyl acetate. The combined extracts were washed with saturated aqueous sodium bicarbonate and then with water, dried over sodium sulfate and evaporated in vacuo. By chromatography on silica gel, 0.21 gm. (75.1% of theory) of 22-fiuoro-digitoxin was obtained, which was identical to the compound obtained in Example 9(b).

EXAMPLE 16 22- fluoro-digoxin penta-tetrahydropyranyl ether Starting from 8 gm. (6.9 millimols) of 3fi-[O-(3,4-di- O tetrahydropyranyl B D digitoxosyl) (1 4) O'- (3 O tetrahydropyranyl B D digitoxosyl) (1- 4)- 0 (3 O tetrahydropyranyl p D digitoxosyl)]- 12fi tetrahydropyranyloxy 14 8,21 dihydroxy 5,8- pregnane-ZO-one and 1.92 gm. (8.96 millimols) of fluorophosphono-acetic acid and condensation 'with 1.96 gm. (9.53 millimols) of dicyclohexylcarbodiimide analogous to Example 1(a), 9.3 gm. of the corresponding a-ketol-phosphonoethyl acetate were obtained. R -value: 0.5 (silica gel; solvent system: ethyl acetate/benzene=4/1).

Upon treating the obtained product with 1.03 gm. (9.15 millimols) of potassium tert.-butylate 2.49 gm. (30% of theory) of the compound named in the title of this example were obtained. R -value: 0.7 (silica gel; solvent system: ethyl acetate/benzene=4/1).

EXAMPLE 17 (a) ZZ-fiuoro-digoxin penta-trimethylsilyl ether Starting from 8 gm. (7.17 millimols) of 35-[O-(3,4-di- O trimethylsilyl B D digitoxosyl) (1- 4) O (3- O trimethylsilyl- 3 D digitoxosyl) (1- 4) O (3- O trimethylsilyl )3 D digitoxosyl)] 14,8,21 dihydroxy-Sfl-pregnane-ZO-one and 2.0 gm. (9.33 millimols) of Z-diethylphosphono-2-fluoro-acetic acid and condensation with 2.04 gm. (9.9 millimols) of dicyclohexylcarbodiimide analogous to Example 1(a), 9.4 gm. of the corresponding a-ketol-phosphono-ethyl acetate were obtained.

R value: 0.2 (silica gel; solvent system: ethyl acetate! benzene=4/1).

Upon treating the obtained product with 1.07 gm. (9.5 millimols) of potassium-tert.-butylate, 2.59 gm. (31% of theory) of the compound named in the title of this part of the example were obtained, which were subjected to chromatography on silica :gel. R -value: 0.6 (silica gel; solvent system: ethyl acetate/benzene=4/ 1).

(b) 22-fl-uoro-digoxin A solution of 2.36 gm. of 22-fluoro-digoxin pentatrimethylsilyl ether in 100 ml. of methanol was admixed with ml. of a buffer solution of pH 2.0 (Citrisol, Merck) and allowed to stand for 60 minutes. The solution was evaporated in vacuo, the residue was taken up in ethyl acetate, and the solution was washed first with aqueous sodium bicarbonate and then with water. After it had been dried over sodium sulfate it was evaporated to dryness in vacuo. 1.31 gm. (80.5% of theory) of 22-fluoro-digoxin were obtained, which was identical to the compound obtained in Example 9(b).

The compounds embraced by Formula I above, have useful pharmacodynamic properties. More particularly, they produce a positive inotropic effect upon the heart of warm-blooded animals, such as guinea pigs. The cardiac activity of the compounds embraced by Formula I was ascertained on isolated spontaneously beating auricles of the guinea pig, using the standard test methods of Knafii- Lenz, Arch. exp. Path. Pharmacol. 135, 259 (1928), and Hatcher, Am. J. Pharmacy 82, 360 (1910).

For pharmaceutical purposes the compounds embraced by Formula I are administered to warm-blooded animals perorally or parenterally as active ingredients in customary dosage unit compositions, that is, compositions in dosage unit form consisting essentially of an inert pharmaceutical carrier and one effective dosage unit of the active ingredient, such as tablets, coated pills, capsules, wafers, powders, solutions, suspensions, emulsions, syrups, suppositories and the like. One effective dosage unit of the compounds according to the present invention is from 0.002. to 0.034 mgm./kg. body weight.

The following example illustrate a few cardiac active pharmaceutical dosage unit compositions comprising a compound of the Formula I as an active ingredient and represent the best modes contemplated of putting the invention into practical use. The parts are part by weight unless otherwise specified.

EXAMPLE 18 Tablets The tablet composition was compound from the following ingredients:

Preparation The digoxin compound was intimately admixed with ten times its weight of lactose. This mixture was admixed with the remaining lactose and with the potato starch, and the resulting mixture was granulated with an aqueous 10 %solution of the gelatin through a screen of 1.5 mm.- mesh size. The granulate was dried at 40 C., again passed through a screen of 1 mm. mesh-size and admixed with the magnesium stearate. The finished composition was compressed into 120 mgm.-tablets in a conventional tablet making machine. Each tablet contained 0.25 mgm. of the digoxin compound and, when perorally administered to a warm-blooded animal of about 60 kg. body weight in need of such treatment, produced a very good positive inotropic action upon the heart.

EXAMPLE 19 Coated pills The pill core composition was compounded from the following ingredients:

Preparation The digitoxin compound was intimately admixed with ten times its weight of lactose, the mixture was admixed with the remaining lactose and the corn starch, and the resulting mixture was granulated through a screen of 1 mm. mesh-size with an aqueous 15% solution of the polyvinyl pyrrolidone. The granulate was dried at 40 C. and again passed through the above screen, admixed with the magnesium stearate, and the composition was compressed into 50 mgm.-pill cores.

The thus prepared cores were coated according to known methods with a shell consisting essentially of sugar and talcum, and the finished coated pills were polished with beeswax. Each pill contained 25 mgm. of the digitoxin compound and, when perorally administered to a warm-blooded animal of about 60 kg. body weight in need of such treatment, produced a very good positive inotropic action upon the heart.

EXAMPLE 20 Coated pills The pill core composition was compounded from the following ingredients:

Parts ZZ-hutoxy-digoxin 0.125 Lactose 32.375 Corn starch 15.000 Polyvinyl pyrrolidone 2.000 Magnesium stearate 0.500

Preparation The coated pills were prepared in a manner analogous to that described in Example 19. Each pill contained 0.125 mgm. of the digoxin compound and, when perorally administered to a warm-blooded animal of about 60 kg. body weight in need of such treatment, produced a very good positive inotropic action upon the heart.

EXAMPLE 21 Drop solution The solution was compounded from the following Preparation The digitoxin compound and the flavoring were dissolved in the ethanol (Solution A). The sorbitol and the saccharin sodium were dissolved in the distilled water (Solution B). Solution A was admixed with Solution B, and the resulting solution was filtered until free from suspended matter. 1 ml. (about 20 drops) of the finished Hypodermic solution The solution was compounded from the following ingredients:

Parts 22-butoxy-digoxin 0.25 Polyethylene glycol 600 tartaric acid 150.0

Distilled water q.s.ad (by vol.) 3000.0

Preparation The tartaric acid, the polyethyleneglycol and the digoxiu compound were dissolved, one after the other, in distilled water. The solution was diluted with distilled water to the indicated volume, and the solution was filtered until free from suspended matter. The filtrate was filled into white 3 mL-ampules in an atmosphere of nitrogen, and the filled ampules were sealed and sterilized for 20 minutes at 120 C. Each ampule contained 0.25 mgm. of the digoxin compound, and when the contents thereof were administered by intravenous injection to a warm-blooded animal of about 60 kg. body weight in need of such treatment, a very elfective positive inotropic action upon the heart was produced.

EXAMPLE 23 Suppositories The suppository composition was compounded from Preparation The digitoxin compound was intimately admixed with the lactose, and the mixture was homogeneously blended with an immersion homogenizer into the cocoa butter which had previously been melted and cooled to 40 C. The composition was then cooled to 37 C., and 1700 mgm.-portions thereof were poured into cooled suppository molds. Each suppository contained 0.25 mgm. of the digitoxin compound and, when administered by the rectal route to a warm-blooded animal of about 60 kg. body weight in need of such treatment, produced a very effective positive inotropic action upon the heart.

Analogous results were obtained when any one of the other cardenolide glycosides embraced by Formula I was substituted for the particular cardenolide glycosides in [Examples 18 through 23. Likewise, the amount of active ingredient in these illustrative examples may be varied to achieve the dosage unit range set forth above, and the amounts and nature of the inert pharmaceutical carrier ingredients may be varied to meet particular requirements.

While the present invention has been illustrated with the aid of certain specific embodiments thereof, it will be readily apparent to others skilled in the art that the invention is not limited to these particular embodiments, and that various changes and modifications may be made without departing from the spirit of the invention or the scope of the appended claims.

We claim:

1. A cardiac-active pharmaceutical dosage unit composition consisting essentially of an inert pharmaceutical carrier and an effective positive inotropic amount of a compound of the formula O CH: l-

F OH H wherein R is hydrogen or hydroxyl.

2. A composition of claim 1, wherein said compound is 22-fluoro-digoxin.

3. A composition of claim 1, wherein said compound is 22-fluoro-digitoxin.

4. The method of producing a positively inotropic action upon the heart of a warm-blooded animal, which comprises administering to said animal an effective positive inotropic amount of a compound of the formula H wherein R is hydrogen or hydroxyl.

5. The method of claim 4, wherein said compound is 22-fluoro-digoxin.

6. The method of claim 4, wherein said compound is 22-fluoro-digitoxin.

References Cited UNITED STATES PATENTS 3,514,441 5/1970 Satoh et al. 260-2105 3,531,462 9/1970 Satoh et al 260210.5 3,538,078 11/1970 Kaiser et a1. 260-2105 RICHARD L. HUFF, Primary Examiner 

